How to Harvest Soybeans with High Moisture: From Field to Storage

Sometimes the right time to harvest soybeans is right now. However, even if your harvest window is closing, there are several things you can do to ensure the moisture content of your soybeans is at the optimal level for storage.

When their moisture content is too high, soybeans can be prone to mold or fungal growth; when it’s too low, beans can be cracked and damaged. Striking the right balance not only protects grain quality but also helps you avoid costly storage issues down the line.

How to harvest soybeans to minimize moisture content issues

Even though soybean stems can still look green, the beans themselves can be dry enough for harvesting. The optimal moisture content is around 13%, though it’s nearly impossible to harvest all your beans at the same uniform level.¹ Delaying harvest to wait for moisture levels to drop can increase the risk of shattering. Even if you leave only a few beans on the ground per square foot, that loss will cut into your profit. For example, just four to five beans on the ground per square foot can add up to the loss of one full bushel per acre.
If you don’t have a way to dry your beans in storage, start harvesting around 14%. If you plan to aerate your soybeans, you can start around 16% and then slowly dry them down to the desired moisture level.²
To reduce potential harvest losses, make sure your cutter bars are sharp and you’ve adjusted your combine. This might mean slowing your ground speed and adjusting as you go along. That way, you can ensure the best yield even in wet conditions.

Effective drying methods after harvesting soybeans

Once you’ve finished harvesting, you’ll have to make some storage decisions based on how long you plan to store your soybeans and what their current moisture content is. If you’re storing soybeans over winter, a 13% moisture content is best. Any longer than that and you’ll want to make sure moisture levels are under 12%. Anything higher can compromise the soybean quality.³
Natural air drying can bring moisture down to the desired 12-13%, but you’ll need to consider both the ambient air temperature and relative humidity. These two factors determine your soybeans’ equilibrium moisture content (EMC), that is, the state in which the beans neither gain nor lose moisture because their moisture content is in equilibrium with the surrounding air’s relative humidity and temperature. Refer to an EMC table to see what temperature and humidity your air needs to be to dry your soybeans down to the right level.⁴
Understanding your soybeans’ EMC is especially important to prevent seed cracking. Soybeans will crack once the drying air humidity drops below 40%. If you are drying soybeans with air at 70 F and 70% relative humidity, you will achieve an EMC of 13.5%. Let’s say you want to achieve 13%; you would need to increase the air-drying temperature to 90 F. However, because relative humidity drops by half with every 20-degree increase in temperature, the relative humidity of 90 F air would be around 35% relative humidity. That would put the soybeans in danger of seed cracking.⁵

How to monitor moisture when storing soybeans

To avoid spoilage or quality loss, it’s important to check soybean moisture content regularly, especially during the first few weeks after harvest. Use a calibrated moisture meter and take readings from multiple points in the bin to account for uneven drying.
Check moisture content every two weeks during the winter and then weekly during the spring and summer. As you monitor moisture, also record any signs of condensation, insect activity, or increasing grain temperatures.⁶

How are soybeans transported to prevent loss?

Once soybeans leave the field or bin, it’s essential that you protect the grain quality while in transit. You can do this by:

• Reducing rough handling or dropping grain to minimize mechanical damage
• Using clean, dry trucks with smooth interior surfaces to prevent contamination or splitting
• Covering the load with a tarp to protect against rain or high humidity
• Transporting during the cooler morning hours⁷

Harvesting soybeans at the right moisture level and handling them carefully from the field to storage can make a big difference in quality and profitability. With the right timing, tools, and monitoring, you can reduce losses and protect your crop every step of the way.
Experts are available to help you make your decisions. Reach out to your seed retailer, a nearby extension office agent, or a seed company professional like your regional BASF representative.

________________________________________________

Endnotes

1. Zoubek, Gary, Roger Wilson, and Chuck Burr. “Managing Soybean Harvest Timing, Moisture to Improve Yield.” CropWatch, University of Nebraska–Lincoln Extension, 21 Sept. 2018, https://cropwatch.unl.edu/managing-soybean-harvest-timing-moisture-improve-yield-0.
2. Zoubek, Wilson, and Burr. “Managing Soybean Harvest Timing, Moisture to Improve Yield.”
3. “Storing Soybeans? Experts Share Best Practices for Long-term Storage.” AgUpdate, 29 Oct. 2018, agupdate.com/tristateneighbor/news/crop/storing-soybeans-experts-share-best-practices-for-long-term-storage/article_04a364ce-d6d7-11e8-9857-2bb13907c9f0.html. ]
4. “On-Farm Soybean Drying and Storage.” University of Arkansas System Division of Agriculture Cooperative Extension Service, https://www.uaex.uada.edu/farm-ranch/crops-commercial-horticulture/Grain_drying_and_storage/soybean_drying_and_storage.aspx.
5. Sadaka, Sammy. “On-Farm Drying and Storage of Soybeans.” University of Arkansas System Division of Agriculture, 2014, https://fyi.extension.wisc.edu/energy/files/2017/10/chapter15-On-Farm-Drying-and-Storage-of-Soybean-2014.pdf.
6. Hellevang, Ken. “Better Soybean Storage Starts With Good Harvest Moisture.” CropWatch, University of Nebraska–Lincoln Extension, 5 Sept. 2018, https://cropwatch.unl.edu/2018/enhancing-soybean-storage-starts-harvest-moisture/.
7. Zoubek, Wilson, and Burr. “Managing Soybean Harvest Timing, Moisture to Improve Yield.”